SB 


MSb 


METHODS  FOR  THE 
ANALYSIS  OF  IRON 
AND  STEEL,  USED 
IN  LABORATORIES 
OF  THE  AMERICAN 
ROLLING  MILL  CO., 
MIDDLETOWN,  OHIO 


RESEARCH  LABORATORY 

THE  AMERICAN  ROLLING  MILL  COMPANY 

MIDDLETOWN.  OHIO 


Copyright,  1912 

The  American  Rolling  Mill  Co. 

Middletown,  Ohio 


Preface 


|E  ARE  ISSUING  THIS  BULLETIN 

on  account  of  the  numerous  requests 
we  receive  for  copies  of  the  methods 
used  in  our  laboratories,  especially 
those  referring  to  the  analysis  of 
pure  American  Ingot  Iron.  Some 
of  the  methods  are  essentially  as 
described  in  the  standard  text  books,  others 
are  entirely  new.  We  have  not  attempted  to 
include  all  the  elements  existing  in  special  steels. 
We  refer  the  chemist  to  standard  text  books 
for  the  methods  of  analysis  not  herein  described. 
This  bulletin  is  intended  as  an  aid  to  experienced 
chemists  who  are  thoroughly  conversant  with 
the  standard  methods  for  the  analysis  of  iron  and 
steel.  For  the  sake  of  brevity  we  have  omitted 
details  which  are  fully  described  in  the  text 
books,  but  in  some  cases  where  we  considered 
it  advisable  we  have  given  minute  details. 
We  invite  criticism  and  suggestions  in  reference 
to  new  or  modifications  of  old  methods,  which 
will  be  duly  credited  to  the  author  if  published 
in  our  future  bulletins. 

Research  Laboratory 

The  American  Rolling  Mill  Company 

Middletown,  Ohio. 


^45990 


Contents 


Determination  of  Silicon 9 

Photomicrograph,  American  Ingot  Iron 10 

Determination  of  Sulphur 11-1*2 

Determination  of  Phosphorus 13-14 

Determination  of  Carbon 15-16 

Determination  of  Manganese 17-18 

Determination  of  Chromium 19-20 

Determination  of  Vanadium 21 

Photomicrograph,  Norway  Iron  from  Newburyport 

Bridge  Link 22 

Gravimetric  Determination  of  Iron 23-27 

Photomicrograph,  Steel 28 

Determination  of  Copper 29-30 

Determination  of  Nitrogen 31-34 

Determination  of  Hydrogen 35-40 

Determination  of  Oxygen  in  Iron  and  Steel 41-50 

Analysis  of  Tin  and  Terne  Plate  and  Lead  Coated 

Sheets 51-55 

Photomicrograph,  Puddled  Iron 56 

Test  to  Indicate  Whether  Metal  is  Iron  or  Steel ....  57-58 
Pin  Hole  Test  — Lead  Coated,  Tin  and  Terne  Plate. . .  59 
Hydrochloric  Acid  Method  for  Determining  Ounces 

of  Spelter  per  Square  Foot 60 

Lead  Acetate  Method  for  the  Determination  of  Spel- 
ter Coating , 61-62 


METHODS   OF  ANALYSIS 


Determination  of  Silicon 

Dissolve  4.69  grams  of  the  sample  in  a  plati- 
num dish,  using  60  c.  c.  of  nitric  acid,  1.18 
specific  gravity,  and  10  c.  c.  of  sulphuric  acid, 
1.84  specific  gravity.  Evaporate  to  dense  white 
fumes  and  allow  to  cool.  Dissolve  ferric  sul- 
phate in  about  35  c.  c.  of  hydrochloric  acid,  1.20 
specific  gravity,  dilute  and  filter.  Filter  on 
ashless  paper  and  wash  alternately  with  distilled 
water  and  dilute  hydrochloric  acid,  1.05  specific 
gravity,  until  free  from  iron.  Ignite  in  platinum 
crucible,  using  a  Meker  burner  with  natural 
draft.  Weigh  residue  and  add  about  1  c.  c.  of 
hydrofluoric  acid  and  about  3  drops  of  concen- 
trated sulphuric  acid.  Heat  crucible  carefully 
until  acid  has  evaporated,  then  to  full  temper- 
ature of  burner  until  iron  has  changed  to  oxide. 
Cool  and  weigh.  The  loss  is  silica.  Each 
milligram  equals  .01%  of  silicon. 


AMERICAN  INGOT  IRON 
Clear  Ferrite,  Medium  Grain,  Absence  of  Slag  and  Gases 


10 


Determination  of  Sulphur 

Dissolve  5  grams  of  the  sample  in  100  c.  c. 
of  hydrochloric  acid,  1.10  specific  gravity,  con- 
tained in  a  500  c.  c.  flask  fitted  with  rubber 
stopper  containing  thistle  tube  and  educt  tube, 
passing  through  a  reflux  condenser  to  prevent 
acid  distilling  over.  The  educt  tube  dips  almost 
to  the  bottom  of  a  10"  x  1"  test  tube  containing 
50  c.  c.  of  cadmium  chloride  solution.  A  low  flame 
is  applied  and  flask  heated  until  all  metal  has 
dissolved  and  all  gas  has  been  driven  out  of 
flask,  as  is  evidenced  by  the  steam  condensing 
in  cadmium  chloride  tube.  The  contents  of 
test  tube  are  washed  into  an  800  c.  c.  beaker 
and  sufficient  water  is  added  to  bring  the 
volume  to  500  c.  c.  Add  5  c.  c.  of  starch  solution 
and  50  c.  c.  of  hydrochloric  acid,  1.20  specific 
gravity.  The  solution  is  then  titrated  with 
standard  iodine  solution  to  blue  color. 

The  standard  iodine  solution  is  prepared  by 
dissolving  8.4  grams  of  iodine  and  20  grams  of 
potassium  iodide  in  50  c.  c.  of  distilled  water. 
When  iodine  is  in  solution  dilute  to  2  liters 
and  standardize  with  steel  of  known  sulphur 
content.  1  c.  c.  should  equal  .01%  of  sulphur 
when  using  5  grams. 

The  starch  solution  should  be  prepared  fresh 
daily,  using  1  gram  of  arrowroot  mixed  in 

11 


10  c.  c.  of  cold  distilled  water,  which  is  poured 
into  100  c.  c.  of  boiling  water  and  immediately 
removed  from  fire. 

The  cadmium  chloride  solution  is  prepared 
by  dissolving  10  grams  of  cadmium  chloride  in 
1500  c.  c.  of  distilled  water  and  500  c.  c.  of  .90 
specific  gravity  ammonia. 


Determination  of  Phosphorus 

Dissolve  2  grams  of  the  sample  in  40  c.  c. 
of  nitric  acid,  1.18  specific  gravity,  using  a  300 
c.  c.  Erlenmeyer  flask.  Heat  on  hot  plate  until 
metal  is  in  solution  and  add  5  c.  c.  of  saturated 
solution  permanganate  of  potash.  Boil  until 
brown  precipitate  is  formed.  Now  add  a  few 
c.  c.  of  hydrochloric  acid,  1.20  specific  gravity,  in 
sufficient  amount  to  clear  the  solution  by  boiling 
a  few  minutes.  Remove  from  hot  plate,  cool 
somewhat,  and  cautiously  add  ammonia,  .90 
specific  gravity,  shaking  flask  occasionally,  until 
a  heavy  precipitate  of  ferric  hydroxide  is  formed. 
Then  add  nitric  acid,  1.42  specific  gravity, 
shaking  occasionally,  until  precipitate  dissolves 
and  a  clear  amber-colored  solution  is  obtained. 
Heat  or  cool  solution  to  85°  C.  and  add  50  c.  c. 
of  ammonium  molybdate  solution.  Shake  well 
and  allow  to  stand  at  least  J/£  hour  or  until 
precipitate  settles.  Filter  and  wash  writh  2% 
nitric  acid  solution  until  free  from  iron,  and  fin- 
ally with  distilled  water  containing  about  1  gram 
of  potassium  nitrate  to  liter  until  free  from  acid. 
Transfer  filter  and  contents  to  tumblercontaining 
50  c.  c.  of  boiled  distilled  water.  Disintegrate 
paper  with  two  stirring  rods  and  add  sufficient 
standard  sodium  hydroxide  to  dissolve  the 
yellow  precipitate  and  render  the  solution  pink 

13 


when  phenolphtalein  indicator  is  added.  Now 
run  in  standard  nitric  acid  until  pink  color 
disappears. 

The  acid  and  alkali  are  about  .15  normal. 
1  c.  c.  is  equal  to  about  .01%  of  phosphorus 
when  2  grams  are  taken  for  analysis.  The  exact 
standardization  of  the  acid  and  alkali  solutions 
is  made  by  the  use  of  steel  standards  prepared 
by  the  U.  S.  Bureau  of  Standards. 

1.18  specific  gravity  nitric  acid  can  be  pre- 
pared by  adding  1  part  of  nitric  acid,  1.42 
specific  gravity,  to  2  parts  of  water. 


u 


Determination  of  Carbon 

The  determination  of  carbon  in  iron  and 
steel  is  made  by  direct  combustion,  using  a 
%"-bore  x  30"  silica  tube  contained  in  an 
electric  furnace.  We  have  found  that  a  gas 
furnace  is  not  reliable  where  the  gas  pressure 
fluctuates  considerably.  This  is  due  to  the 
danger  of  overheating  and  causes  devitrification 
of  the  silica  tube,  with  a  consequent  loss  of 
carbon. 

When  determining  traces  of  carbon  the 
greatest  care  is  necessary  in  order  to  secure 
accurate  determinations. 

The  carbon  dioxide  is  absorbed  in  potas- 
sium hydrate,  and  care  must  be  taken  to  always 
weigh  the  bulbs  under  the  same  conditions. 
If  the  bulb  contains  air  during  the  first  weighing 
and  oxygen  during  the  second,  the  error  in 
weighing  will  amount  to  several  hundredths  of 
a  per  cent. 

We  use  a  6"  x  J^l!  x  ^"  platinum  boat  for 
holding  the  borings,  and  we  can  conveniently 
use  5  grams  of  the  sample  for  a  direct  deter- 
mination of  carbon.  The  boat  is  covered  for  a 
depth  of  y^  with  60-mesh  alundum,  on  which 
the  borings  are  placed;  we  then  cover  the 
borings  completely  with  alundum  and  burn 
for  30  minutes  at  950°  C. 


We  have  found  that  a  short  alundum  thimble 
inserted  in  the  ^"-bore  silica  tube  next  to  the 
stopper  will  prevent  radiated  heat  from  acting 
on  the  rubber  stopper. 

Carbon  can  also  be  determined  by  color  as 
follows : 

In  determining  carbon  by  color  it  is  essen- 
tial that  the  standard  contain  approximately 
the  same  per  cent  carbon  as  the  sample,  and 
also  that  the  materials  have  had  the  same  heat 
treatment.  For  the  analysis  of  pure  iron  we 
furnish  free  a  vial  of  standardized  American 
Ingot  Iron. 

Dissolve  j/2  gram  of  the  sample  and  }/2  gram 
of  the  standard  in  10  c.  c.  of  nitric  acid,  1.18 
specific  gravity,  contained  in  separate  10"  x  1" 
test  tubes.  Heat  over  Bunsen  flame  until 
metal  has  dissolved  and  tubes  are  free  from 
brown  fumes.  Cool  carefully  and  pour  into 
carbon  comparison  tubes.  Match  color  of  stand- 
ard with  the  color  of  sample  by  diluting  with 
distilled  water.  Knowing  the  carbon  content 
of  standard  the  carbon  of  sample  can  be  easily 
calculated. 


H; 


Determination  of  Manganese 

Titration  Method 

This  is  the  bismuthate  method  as  perfected 
by  Professor  D.  J.  Demorest,  of  the  Ohio  State 
University,  which  is  substantially  as  follows: 

Dissolve  1  gram  of  the  sample  in  45  c.  c. 
of  water  and  15  c.  c.  of  nitric  acid,  1.42  specific 
gravity,  and  boil  until  nitrous  fumes  are  gone. 
After  cooling  somewhat,  sodium  bismuthate  is 
added,  a  little  at  a  time,  until  the  resulting  per- 
manganic acid  or  manganese  dioxide  persists  after 
a  few  minutes  boiling.  Now  3  c.  c.  of  a  5% 
solution  of  potassium  nitrite  is  added  to  reduce 
the  manganese  compounds,  and  the  solution  is 
boiled  a  few  minutes  to  expel  the  nitrous  fumes. 
It  is  then  cooled  to  tap  water  temperature. 
When  cold,  sodium  bismuthate  is  added,  a 
little  at  a  time,  while  the  solution  is  shaken, 
until  about  }/2  gram  has  been  added.  After 
settling  a  few  minutes  the  solution  is  filtered 
by  suction  through  asbestos  on  glass  wrool 
contained  in  a  3"  funnel  (or  an  alundum 
crucible  can  be  used) .  The  filter  is  well  washed 
with  a  3%  solution  of  nitric  acid  prepared  from 
colorless  acid.  The  permanganic  acid  is  then 
titrated  with  standard  sodium  arsenite  solution 
until  the  pink  tinge  just  disappears.  There 


should   not   be   a   brownish   color   at   the   end. 
If  there  is,  it  indicates  insufficient  acid. 

The  sodium  arsenite  is  prepared  by  dis- 
solving 2  grams  of  arsenious  acid  in  a  hot 
solution  of  sodium  carbonate,  using  sufficient 
sodium  carbonate  to  completely  dissolve  the 
arsenious  acid.  It  is  then  filtered  through 
paper  and  diluted  to  2  liters.  1  c.  c.  is  approxi- 
mately equal  to  .00025  gram  of  manganese. 
The  solution  is  standardized  against  steel  of 
known  manganese  content. 

By  Color 

Dilute  the  solutions  from  carbon  determina- 
tion to  30  or  40  c.  c.  Remove  10  c.  c.  from 
each  with  a  pipette,  place  in  10"  x  1"  test 
tubes  and  add  to  each  3  c.  c.  of  nitric  acid,  1.18 
specific  gravity.  Bring  to  boil  and  add  ^ 
gram  of  lead  peroxide  (free  from  manganese)  to 
each  and  boil  vigorously  for  3  minutes.  Cool 
and  pour  into  15  c.  c.  centrifuge  tubes  and 
separate  the  undissolved  lead  peroxide  by 
centrifuging  a  few  minutes.  Decant  clear  solu- 
tion into  comparison  tubes  and  dilute  until 
colors  match.  If  no  centrifuge  is  available  the 
lead  peroxide  can  be  filtered  out  on  an  alundum 
crucible  or  on  an  ignited  asbestos  filter  either  of 
the  Gooch  or  cone  type. 


18 


Determination  of  Chromium 

This  method  is  based  on  the  fact  that 
chromium  and  manganese  are  oxidized  by 
sodium  bismuthate  in  either  nitric  acid,  sul- 
phuric acid,  or  a  mixture  of  nitric  and  sulphuric 
acids.  Nitric  acid  alone  is  generally  used, 
and  only  in  rare  instances  will  it  be  necessary 
to  add  'sulphuric  acid  to  facilitate  the  solution 
of  the  metal.  Some  manganese  is  oxidized  to 
permanganic  acid,  which  is  decomposed  by 
boiling,  forming  nitrate  of  manganese  and 
manganese  dioxide.  The  manganese  dioxide  is 
removed  by  filtration  through  asbestos,  washing 
the  asbestos  well  with  a  3%  solution  of  nitric 
acid.  If  any  chromium  is  present  it  will  be 
indicated  by  a  yellow  color  in  the  filtrate. 

Dissolve  3  grams  of  the  sample  in  a  mixture 
of  70  c.  c.  of  water  and  30  c.  c.  of  nitric  acid, 
1.42  specific  gravity.  Boil  until  metal  is  in  solu- 
tion. Cool  slightly  and  add  2  grams  of  sodium 
bismuthate,  taking  care  to  wash  all  bismuthate 
from  the  neck  of  the  flask.  Boil  for  15  minutes, 
or  until  permanganic  acid  is  decomposed.  Filter 
with  suction  on  asbestos  supported  by  a  tuft 
of  glass  wool  in  a  3"  glass  funnel.  Wash 
with  3%  nitric  acid.  Cool  to  tap  water  tem- 
perature and  dilute  to  500  c.  c.  with  distilled 
water.  Add  a  measured  excess  of  ferrous 


ammonium  sulphate  solution  until  free  from 
yellow  tints.  Titrate  the  excess  with  standard 
permanganate  to  faint  pink  color  that  persists 
for  30  seconds. 

Titrate  with  permanganate  50  c.  c.  of 
ferrous  ammonium  sulphate  containing  the  same 
amount  of  acid  and  water  as  the  test. 

The  amount  of  ferrous  ammonium  sulphate 
oxidized  by  the  chromic  acid  and  measured  in 
terms  of  permanganate  is  multiplied  by  the  iron 
factor  x  .31,  or  1  c.  c.  of  tenth  normal  potassium 
permanganate  equals  .00173  gram  of  chromium. 

The  ferrous  ammonium  sulphate  is  pre- 
pared by  dissolving  50  grams  of  the  salt  in  2 
liters  of  10%  by  volume  of  sulphuric  acid. 
When  this  strength  solution  is  used,  1  c.  c. 
will  equal  about  %  c.  c.  of  tenth  normal 
permanganate. 

The  following  table  indicates  the  accuracy 
of  the  method,  showing  in  some  instances  a  very 
small  per  cent  of  chromium  in  the  presence  of 
a  very  high  per  cent  of  manganese: 


Chromium  Added 

Chromium  Found 

Manganese 

1.44 

1.42 

.67 

1.44 

1.48 

.01 

.37 

.37 

.38 

.33 

.35 

.55 

.29 

.31 

.75 

.24 

.26 

.95 

.12 

.11 

1.30 

.04 

.04 

1.90 

20 


Determination  of  Vanadium 

Vanadium  can  be  determined  in  the  same 
solution  as  the  chromium  as  described  by 
C.  M.  Johnson  in  his  book  "Chemical  Analysis 
of  Steel,"  which  is  essentially  as  follows: 

To  the  flask  containing  the  solution  from 
the  chromium  determination,  add  3  c.  c.  of  a 
1%  solution  of  potassium  ferricyanide.  Stand- 
ard ferrous  ammonium  sulphate  is  now  added 
from  a  burette  until  1  drop  produces  a  green 
coloration. 

A  blank  determination  is  made  on.  steel  free 
from  vanadium.  This  blank  varies  from  .4  to 
1  c.  c.  of  ferrous  ammonium  sulphate  and  should 
be  deducted  before  making  the  calculations. 

The  amount  of  ferrous  ammonium  sulphate 
used  in  terms  of  potassium  permanganate  is 
equivalent  to  .00512  grams  of  vanadium  for  a 
tenth  normal  permanganate  solution. 


NORWAY  IRON  FROM  NEWBURYPORT  BRIDGE  LINK 

After  100  Years'  Service.     Clear  Ferrite,  Medium  Grain 
Very  Little  Slag  and  Free  from  Gases 


Gravimetric  Determination  of  Iron 

Dissolve  about  1  gram1  of  the  sample, 
accurately  weighed,  in  a  600  c.  c.  Jena  glass 
beaker2,  on  the  water  bath,  using  25  c.  c.  of  a 
10%  solution  of  hydrochloric  acid.  When  solu- 
tion is  complete,  add  200  c.  c.  of  distilled  water, 
heat  on  water  bath  to  about  80°  C.  and  pass  a 
moderate  current  of  hydrogen  sulphide  gas 
through  the  solution  for  20  minutes.  Remove 
from  water  bath,  add  200  c.  c.  more  of  cold 
distilled  water,  and  continue  the  stream  of 
hydrogen  sulphide  for  another  20  minutes,  or 
until  the  solution  is  cold.  Filter  from  the  pre- 
cipitate and  wash  thoroughly  with  hydrogen 
sulphide  water  containing  a  small  amount  of 
hydrochloric  acid3,  collecting  the  filtrate  in  an 
800  c.  c.  Jena  glass  beaker2.  Test  the  residue 


1.  By   employing    a  power-driven   centrifuge    of   large   capacity   the 
washing  of  precipitate  can  be  perfectly  and  quickly  performed  largely  by 
decantation,  thereby  enabling  the  operator  to  use  a  sample  as    large 
as  5  grams. 

2.  Beakers,  funnels,  watch  glasses  and  glass  rods  must  be  thoroughly 
cleaned  with  warm  concentrated  hydrochloric  acid  before  use,  in  order 
to  prevent  any  foreign  iron  from  entering  the  solutions. 

3.  The  presence  of  acid  is  necessary  to  secure  a  perfect  removal  of  iron 
from  the  residue  and  the  filter  paper.     The  hydrogen  sulphide  removes 
the  following  elements:    silver,  lead,  mercury,  gold,  platinum,  tin,  anti- 
mony, arsenic,   copper,   cadmium,   bismuth,    molybdenum,    tellurium, 
selenium,  germanium,  iridium,  osmium,  palladium,  rhodium,  ruthenium, 
tungsten,  vanadium. 


for  iron4.  Evaporate  the  filtrate  on  the  water 
bath  until  the  volume  is  reduced  to  about 
200  c.  c.  and  all  the  hydrogen  sulphide  is  driven 
off.  Then  add  5  c.  c.  of  concentrated  nitric 
acid  and  10  c.  c.  of  concentrated  hydrochloric 
acid'%  and  heat  to  about  90°  C.  on  the  water 
bath  and  add  a  slight  excess  of  warm  dilute 
ammonia6.  Allow  the  precipitate  to  settle, 
decant  through  a  15  ctm.  ashless  filter,  transfer 
the  precipitate  to  the  filter7  and  wash  with 
boiling  water  until  5  c.  c.  of  the  washings  give 
no  opalescence  with  silver  nitrate8.  (Collect 
the  filtrate  and  the  first  washings  in  a  clean 
800  c.  c.  beaker  and  reserve  for  determination 
of  manganese).  Dry  the  ferric  hydroxide  pre- 
cipitate at  95-100°  C.9  and  then  separate  as 
perfectly  as  possible  from  the  filter  paper,  in  a 
room  free  from  draught,  placing  the  dry  ferric 
hydroxide  in  a  small  porcelain  dish  on  a  white 
glazed  paper.  Cover  the  porcelain  dish  with  a 


4.  If  great  accuracy  is  desired,  the  analysis  should  be  rejected  when- 
ever more  than  traces  of  iron  are  detected  in  the  sulphide  residue. 

5.  The  nitric  acid  is  added  to  oxidize  the  iron,   and  the  hydrochloric 
acid  to  secure  sufficient  ammonium  chloride  to  keep  zinc,  cobalt,  nickel 
and  part  of  the  manganese  in  solution.     In  nickel  steels  the  precipita- 
tion should  be  repeated  several  times. 

6.  A  large  excess  of  ammonia  is  objectionable,  as  it  causes  some  of 
the  iron  to  become  colloidal. 

7.  Ferric  hydroxide  adheres  to  the  beaker  and  the  glass  rod.     In  order 
to  remove  this  quantitatively,  a  few  drops  of  concentrated  nitric  acid 


watch  glass  and  then  ignite  the  filter  paper  in  a 
weighed  porcelain  crucible.  Transfer  the  pre- 
cipitate from  the  porcelain  dish  to  the  crucible: 
cover  with  a  platinum  cover  and  ignite  for  10 
minutes  over  a  Bunsen  burner;  remove  the 
cover,  incline  the  crucible  slightly  and  ignite 
for  another  10  minutes.  Place  in  desiccator, 
cool  and  weigh.  Repeat  the  ignition  until  the 
weight  remains  constant,  taking  care  not  to 
heat  more  than  a  few  minutes  at  a  time  and  not 
at  too  high  temperature1  °. 

In  the  meantime  evaporate  the  filtrate  for 
the  determination  of  manganese,  to  about  200 
c.  c.  Add  ammonia,  heat  to  boiling  and  pre- 
cipitate the  manganese  with  a  saturated  solution 
of  bromine.  Boil  for  a  few  minutes,  filter  on  a 
small  ashless  filter,  ignite  and  weigh  as  Mn3  O4. 


are  introduced  into  the  beaker  and  by  means  of  the  glass  rod  all  ferric 
hydroxide  is  easily  brought  in  solution.  After  dilution  with  water  the 
iron  is  reprecipitated  with  ammonia  and  transferred  to  the  filter. 
Nitric  acid  is  used  in  order  to  prevent  introduction  of  chlorides  (see  8) . 

8.  When  iron  is  precipitated  with  ammonia,  small  amounts  of  basic 
iron  salts  are  always  thrown  down  with  the  hydroxide.  The  amount 
and  the  composition  of  the  basic  salts  vary  according  to  the  conditions. 
Thus  in  a  solution  of  sulphate  of  iron  larger  amounts  of  basic  salts  are 
formed  than  from  solutions  of  ferric  nitrate  or  chloride.  In  a  cold 
solution  more  basic  salts  are  formed  than  when  the  solution  is  nearly 
boiling,  and  in  addition  the  ferric  hydroxide  tends  to  assume  a  colloidal 
state,  especially  in  the  presence  of  a  large  excess  of  ammonia.  Basic 
chloride  of  iron  is  volatile  on  ignition,  hence  the  necessity  of  eliminat- 
ing chlorides.  Warm  water  decomposes  chloride  of  iron,  leaving  the 
hydroxide  free  from  chlorine. 

25 


This  weight  subtracted  from  the  weight  of 
Mn3  O4  in  the  sample,  calculated  from  the  total 
manganese,  gives  the  amount  of  Mn3  O4  in  the 
ferric  oxide. 

To  determine  silica  in  the  ignited  precipitate, 
transfer  this  to  a  small  platinum  dish  and 
digest  with  concentrated  hydrochloric  acid  on 
the  water  bath  and  evaporate  to  dryness 1 l . 
Redissolve,  dilute  with  hot  water  and  filter  from 
the  silica  on  a  small  ashless  filter.  Wash  with 
hot  dilute  hydrochloric  acid  and  hot  water 
until  the  silica  is  free  from  iron.  Ignite  in  a 
platinum  crucible,  cool  and  weigh,  and  then 
evaporate  with  2  drops  of  sulphuric  and  1  c.  c. 
of  hydrofluoric  acid;  ignite,  cool  and  weigh. 


9.  The  filter  paper  will  become   brittle    if   heated    at    a    temperature 
above  100°  C.     Dry  at  least  10  hours.     Heat  gradually  in  crucible. 

10.  When  ferric  oxide  is  ignited  at  too  high  a  temperature,  some  mag- 
netic oxide  of  iron  (Feg  04  )  is  always   formed,   causing  low  results. 
The  formation  of  magnetic  oxide  takes  place  much  more  readily  when 
the  ignition  is  performed  in  a  platinum  crucible     A  convenient  arrange- 
ment consists  of  placing  a  small   porcelain    crucible  within  a  covered 
platinum  crucible,  whereby  the  contact  with  platinum  is  avoided  and 
the  danger  of  overheating  greatly  reduced  ;  at  the  same  time  the  disad- 
vantage of  using  a  porcelain  crucible  alone  is  overcome. 

11.  If  the  oxide  has  been  heated  to  a  high  temperature  it  is  difficult  to 
dissolve   in   concentrated  hydrochloric  acid.     To  secure  solution  in  a 
reasonable  length  of  time  in  cases  when  the  oxide  has  been  overheated, 
it  is  advisable  to  grind  the  oxide  carefully  in  an  agate  mortar  and  then 
ignite  it  for  a  minute,  re  weigh  and  determine  the  silica  on  this  portion 
and  from  the  result  calculate  the  silica  in  the  original  amount  of  oxide. 


The  difference  between  the  two  weighings  then 
represents  the  amount  of  silica  in  the  ferric 
oxide1 2. 

The  total  amount  of  silica,  manganese 
oxide,  chromic  oxide,  phosphoric  acid  and 
alumina  (calculated  from  analysis),  subtracted 
from  the  weight  of  impure  ferric  oxide,  gives 
the  weight  of  pure  Fe2  O3,  which  contains 
69.94%  iron  (Fe=55.84). 


12.  In  all  exact  gravimetric  determinations  of  iron,  allowance  must  be 
made  for  silica  in  the  ferric  oxide.  Most  steel  and  iron  contain  silicon, 
and  considerable  amounts  are  always  dissolved  from  the  glassware 
during  the  chemical  operations.  Glass  is  readily  attacked  by  warm 
ammonia.  Part  of  the  silica  is  undoubtedly  derived  from  the  ammonia 
which  ordinarily  has  been  in  contact  with  common  glass.  Most  of  the 
phosphorus  is  evolved  during  the  solution  in  hydrochloric  acid.  If, 
however,  the  sample  contains  more  than  a  few  thousandths  of  1% 
of  phosphorus,  the  ferric  oxide  should  be  analyzed  for  phosphorus. 
This  can  be  done  in  the  filtrate  from  the  determination  of  silica,  and 
the  amount  found,  figured  to  phosphoric  anhydride,  added  to  the 
other  impurities. 

27 


*;  '  k 
4',-  •  -V 


STEEL 
Showing  Presence  of  Gases 


Determination  of  Copper 

Take  the  filtrate  from  the  determination  of 
sulphur  and  add  ammonia,  .90  specific  gravity, 
until  solution  becomes  light  brown.  If,  however, 
any  precipitate  separates,  add  sufficient  dilute 
hydrochloric  acid  to  dissolve  it,  then  add  water 
to  bring  volume  to  about  400  c.  c,  Pass 
hydrogen  sulphide  gas  into  solution  until  it 
smells  strongly  of  this  gas.  Filter  and  wash 
sulphides  with  hydrogen  sulphide  water.  Open 
paper  against  side  of  funnel;  add  20  c.  c.  of  hot 
nitric  acid,  1.18  specific  gravity*,  to  paper  in  fun- 
nel, allowing  same  to  run  into  original  flask;  wash 
paper  with  dilute  hydrochloric  acid,  evaporate 
solution  to  about  15  c.  c.,  remove  from  heat  and 
add  ammonia,  .95  specific  gravity,  until  iron 
is  precipitated  and  solution  smells  of  ammonia. 
Filter  into  a  100  c.  c.  Nessler  tube  and  wash 
with  hot  water.  The  copper  will  be  found  in 
filtrate  as  a  blue  solution.  To  another  Nessler 
tube  add  about  50  c.  c.  of  distilled  water  and 
5  c.  c.  of  .90  specific  gravity  ammonia.  Then 
add,  from  a  burette,  standard  copper  sulphate 
solution  until  the  colors  match  when  diluted 
to  same  volume. 


*If  stronger  nitric  acid  is  used  it  acts  upon  the  filter  paper,  prevent- 
ing all  the  iron  from  being  precipitated  with  ammonia  and  producing 
an  off-color  difficult  to  match. 

29 


In  material  containing  low  copper  there  may 
be  some  difficulty  in  matching  the  colors,  but 
this  can  be  overcome  by  adding  a  few  drops  of 
a  10%  solution  of  potassium  ferro-cyanide  and 
sufficient  dilute  sulphuric  acid  to  faint  acidity. 
The  reddish  brown  colors  are  then  compared. 

The  standard  copper  sulphate  solution  is  pre- 
pared by  dissolving  7.856  grams  of  crystallized 
copper  sulphate  in  about  200  c.  c.  of  distilled 
water  and  10  c.  c.  of  nitric  acid,  1.42  specific 
gravity.  The  solution  is  then  diluted  to  1  liter. 
Each  c.  c.  equals  .04%  copper  when  5  grams 
have  been  taken  for  analysis. 


30 


Determination  of  Nitrogen 

We  use  the  Allen  method  perfected  by  Pro- 
fessor J.  W.  Langley.  This  method  is  based  on  the 
reaction  by  which  the  combined  nitrogen  in  iron 
or  steel  is  estimated  as  ammonia  by  the  solution 
of  the  metal  in  hydrochloric  acid. 

The  reagents  required  are: 

Hydrochloric  acid  of  1.1  specific  gravity,  free 
from  ammonia,  which  may  be  prepared  by 
distilling  pure  hydrochloric  acid  gas  into  distilled 
water  free  from  ammonia.  To  do  this,  take  a 
large  flask  fitted  with  a  rubber  stopper  carrying 
a  separatory  funnel  tube  and  an  evolution 
tube.  Place  in  the  flask  strong  hydrochloric  acid, 
connect  the  evolution  tube  with  a  wash  bottle 
connected  with  a  bottle  containing  the  distilled 
water.  Admit  strong  sulphuric  acid  free  from 
nitrous  acid,  to  the  flask  through  the  funnel 
tube,  apply  heat  as  required,  and  distil  the  gas 
into  the  prepared  water. 

Test  the  acid  by  admitting  some  of  it  into 
the  distilling  apparatus,  described  further  on, 
and  distilling  it  from  an  excess  of  pure  caustic 
soda,  or  determine  the  amount  of  ammonia  in 
a  portion  of  hydrochloric  acid  of  1.1  specific 
gravity,  and  use  the  amount  found  as  a 
correction. 


Solution  of  caustic  soda,  made  by  dissolving 
300  grams  of  fused  caustic  soda  in  500  c.  c. 
of  water,  and  digesting  it  for  24  hours  at  50°  C. 
on  a  copper-zinc  couple  prepared  by  rolling- 
together  about  6  square  inches  each  of  zinc 
and  copper  foil. 

Nessler  reagent.  Dissolve  35  grams  of  potas- 
sium iodide  in  a  small  quantity  of  distilled 
water,  and  add  a  strong  solution  of  mercuric 
chloride  little  by  little,  shaking  after  each 
addition,  until  the  red  precipitate  formed  dis- 
solves. Finally  the  precipitate  formed  will  fail 
to  dissolve;  then  stop  the  addition  of  the  mer- 
cury salt  and  filter.  Add  to  the  filtrate  120 
grams  of  caustic  soda  dissolved  in  a  small 
amount  of  water,  and  dilute  until  the  entire 
solution  measures  1  liter.  Add  to  this  5  c.  c. 
of  a  saturated  aqueous  solution  of  mercuric  chlo- 
ride, mix  thoroughly,  allow  the  precipitate 
formed  to  settle,  and  decant  or  siphon  off  the 
clear  liquid  into  a  glass-stoppered  bottle. 

Standard  ammonia  solution.  Dissolve  .0382 
gram  of  ammonium  chloride  in  1  liter  of  water. 
1  c.  c.  of  this  solution  will  equal  .01  milligram 
of  nitrogen. 

Distilled  water  free  from  ammonia.  If  the 
ordinary  distilled  water  contains  ammonia, 
redistil  it,  reject  the  first  portions  coming  over, 
and  use  the  subsequent  portions,  which  will  be 

32 


found  free  from  ammonia.  Several  glass  cylin- 
ders of  colorless  glass  of  about  160  c.  c.  capacity 
are  required. 

The  best  form  of  distilling  apparatus  con- 
sists of  an  Erlenmeyer  flask  of  about  1500  c.  c. 
capacity,  with  a  rubber  stopper  carrying  a 
separatory  funnel  tube  and  an  evolution  tube, 
the  latter  connected  with  a  condensing  tube, 
around  which  passes  a  constant  stream  of  cold 
water.  The  inside  tube  where  it  issues  from 
the  condenser  should  be  sufficiently  high  to 
dip  into  one  of  the  glass  cylinders  placed  on  the 
working  table. 

The  determination  of  nitrogen  is  made  as 
follows:  Place  40  c.  c.  of  the  caustic  soda, 
which  has  been  treated  with  the  copper-zinc 
couple,  in  the  Erlenmeyer  flask,  add  500  c.  c. 
of  water  and  about  25  grams  of  tinfoil  to 
prevent  bumping,  and  distil  until  the  distillate 
gives  no  reaction  w^ith  the  Nessler  reagent. 
While  this  part  of  the  operation  is  in  progress 
dissolve  3  grams  of  the  carefully  washed  drillings 
in  30  c.  c.  of  the  prepared  hydrochloric  acid, 
using  heat  if  necessary.  Transfer  the  solution 
to  the  bulb  of  the  separatory  funnel  tube,  and 
when  the  soda  solution  is  free  from  ammonia, 
very  slowly  drop  the  ferrous  chloride  solution 
into  the  boiling  solution  in  the  flask.  When 
about  50  c.  c.  of  water  has  been  collected  in 

33 


the  cylinder,  remove  it  and  substitute  another 
cylinder.  Place  lj/2  c.  c.  of  the  Nessler  reagent 
in  a  cylinder,  dilute  the  distillate  to  100  c.  c. 
with  the  special  distilled  water  and  pour  it  into 
the  cylinder  containing  the  Nessler  reagent. 
Take  another  cylinder,  place  therein  1^/2  c-  c- 
of  the  Nessler  reagent  and  100  c.  c.  of  the 
special  distilled  water  to  which  1  c.  c.  of  the 
ammonium  chloride  solution  has  been  added, 
and  compare  the  colors  of  the  solutions  in  the 
two  cylinders.  If  the  solution  in  the  cylinder 
containing  the  ammonium  chloride  solution  is 
lighter  in  color  than  that  in  the  cylinder  con- 
taining the  distillate,  place  1^  c.  c.  of  the 
Nessler  reagent  in  another  cylinder,  pour  into 
it  100  c.  c.  of  water  containing  2  or  more  c.  c. 
of  the  ammonium  chloride  solution,  and  repeat 
this  operation  until  the  colors  of  the  solutions 
in  the  two  cylinders  correspond  after  standing 
about  10  minutes.  When  about  100  c.  c.  have 
distilled  into  the  second  cylinder,  replace  it  and 
test  as  before.  Continue  the  distillation  until 
the  water  comes  over  free  from  ammonia,  then 
add  together  the  number  of  c.  c.  of  ammonia 
solution  used,  divide  the  sum  by  3,  and  each 
.01  milligram  will  be  equal  to  .001%  of  nitro- 
gen in  the  steel. 


34 


Determination  of  Hydrogen 

The  method  for  determining  hydrogen  by 
heating  the  metal  in  a  partial  vacuum  and 
measuring  the  liberated  hydrogen  is  very  labori- 
ous. The  hydrogen  existing  as  ammonia  would 
not  be  estimated  by  the  above  method. 

Hydrogen  is  kinetically  the  most  active 
element.  Some  of  the  hydrogen  is  liberated  by 
drilling,  so  that  it  is  necessary  to  work  with  the 
metal  in  a  single  piece,  if  possible.  However, 
if  the  metal  is  in  strips,  several  can  be  used  for 
an  analysis. 

The  method  is  based  on  the  fact  that 
hydrogen  is  liberated  by  heating  the  metal  to  a 
red  heat  in  an  atmosphere  of  oxygen.  The 
hydrogen  is  oxidized  to  water,  which  is  absorbed 
in  phosphoric  anhydride. 

The  apparatus  used  consists  of  a  12"  gas 
blast  furnace  in  which  is  placed  a  30"  x  ^" 
silica  tube,  and  on  top  of  this  tube  is  placed  a 
30"  x  ^4"  silica  tube.  The  silica  tubes  each 
have  a  6"  roll  of  platinum  gauze  to  act  as  a 
catalyzer.  The  oxygen  gas  passes  through  the 
M"  silica  tube  (T-2)  at  the  rate  of  100  c.  c. 
per  minute,  and  the  impurities  are  thus  oxidized. 
The  gas  then  passes  through  a  wash  bottle 
containing  a  strong  solution  of  caustic  potash 
(K>2),  then  through  a  bottle  containing  stick 

35 


caustic  potash  (K),  then  through  a  bottle 
containing  concentrated  sulphuric  acid  (S-l). 
and  finally  through  a  tube  containing  phos- 
phoric anhydride  opened  up  with  glass  wool 
(P-l).  The  purified  oxygen  then  enters  the 
%"  silica  tube  (T-l),  where  it  combines  with 
the  liberated  hydrogen,  forming  water,  which 
is  swept  into  the  4"  glass  stop-cock  U-tube 
containing  phosphoric  anhydride  opened  up 
with  glass  wool  (P-2) .  This  tube  is  weighed  and 
connected  with  a  tube  of  phosphoric  acid 
opened  up  with  glass  wool  (P-3)  used  as  a 
trap.  The  gas  finally  passes  through  a  solution 
of  concentrated  sulphuric  acid,  which  is  used 
to  show  that  the  gas  is  passing  through  the 
apparatus. 

The  silica  tubes  should  be  at  a  red  heat 
and  oxygen  passing  through  the  apparatus  at 
the  rate  of  100  c.  c.  per  minute.  Place  in 
either  a  clay  boat,  or  one  of  platinum  containing 
ignited  alundum,  the  sample  in  as  large  pieces 
as  are  available,  using  from  10  to  40  grams  for 
a  determination. 

Weigh  U-tube  (P-2)  and  connect  direct  with 
stopper  to  ^4"  silica  tube.  Remove  stopper  and 
tube  (P-l)  and  insert  the  boat  into  the  red-hot 
zone  of  the  silica  tube.  Connect  tube  (P-l) 
with  silica  tube  and  continue  passing  the 
oxygen  gas  through  the  apparatus  at  the  rate 


36 


of  100  c.  c.  per  minute  for  30  minutes.  At 
the  end  of  this  time  disconnect  weighing  tube 
(P-2)  and  connect  with  a  suitable  aspirator, 
so  as  to  suck  out  the  oxygen  and  replace  it 
with  dry  air.  A  suitable  aspirator  consists  of 
a  1 -gallon  aspirator  bottle  filled  with  water. 
The  upper  tubular  is  guarded  with  a  calcic 
chloride  tube  to  which  the  weighing  tube  is 
connected,  and  the  other  side  of  weighing  tube 
is  connected  with  a  phosphoric  acid  tube  fol- 
lowed by  a  washing  bottle  containing  concen- 
trated sulphuric  acid. 

The  aspirator  may  be  roughly  calibrated  by 
allowing  500  c.  c.  of  water  to  run  out  of  the 
lower  tubular  of  the  aspirator.  This  is  a  sufficient 
amount  of  dry  air  to  thoroughly  displace  all 
the  oxygen. 

The  glass  stop-cocks  of  weighing  tube  are 
now  closed  and  weighing  tube  disconnected 
from  guard  tube  and  placed  in  a  desiccator 
for  15  minutes  before  being  weighed.  One- 
ninth  of  the  increased  weight  of  the  tube  is 
hydrogen. 

It  is  absolutely  necessary  to  run  a  blank 
determination  using  the  same  amount  of  oxygen 
as  for  a  regular  test,  and  it  must  also  be  run 
for  the  same  length  of  time.  The  blank  should 
never  exceed  1  milligram.  This  blank  is 
derived  from  the  oxidation  of  the  rubber  con- 


38 


nections,  hence  the  necessity  for  using  a  definite 
amount  of  oxygen  for  a  definite  length  of  time. 

In  charging  the  weighing  tube  with  phos- 
phoric anhydride,  place  about  a  gram  on  glass 
wool,  fold  the  glass  wool  over  the  phosphoric 
acid  and  insert  into  the  tube.  Repeat  until 
the  tube  is  full.  Use  great  care  to  remove  all 
specks  of  phosphoric  acid  from  the  induct  and 
educt  tubes  of  weighing  tube. 

The  temperature  of  the  silica  tubes  must  be 
regulated  so  that  the  sample  does  not  absorb 
all  the  oxygen.  If  the  temperature  is  too  high 
this  will  occur  and  no  oxygen  will  pass  through 
the  apparatus. 

It  is  not  necessary  to  burn  all  the  metal  to 
oxide;  the  time  that  would  be  required  to 
do  so  would  be  prohibitive  on  large  samples. 


--H        O 


G*        T-H        O        !-H        O 

o    o    o    o    o 


g  s 


o    o 


•s 

-a 


- 

a 


OS 


§  § 


O*     O     GO     X 
i>     G^      O*      G* 

O     O     O     O 


o    o    o    o 

*O     G$     fH     O 

GO     O     O     O 


I 


73 


O     O  .  iO     O 

T-H         <5J         i— I         T-H 

O     I-H     o     O 


r-H     GO     CC 
O       r^       § 


O     G^     i>     »O     GO 

O^      i>     T-H      i— i      O 

ooooo 


GO 


g  ll-J 

hH     hH     ^D       JH 

^     ^       >,    5 

O      O      £?  *t3 
blD     bJD     0)      ^ 

-  «   ^  « 

i  I  P  .2 


^ 

§ 

1 

fr 


I  ^    1    I  '•§  *£   8 

n    •*->     rs     *~i     >*    >*  T-! 


cc 

o3      o3      o3      o3*     -M     -M 
bC     b£     bO     &C     g      g 

2  S  S  S  S  3 

40 


Determination  oi  Oxygen  in 
Iron  and  Steel* 

The  determination  of  oxygen  in  iron  and 
steel  has  not  received  sufficient  attention  in  the 
United  States.  The  text  books  on  iron  and 
steel  analysis  which  are  in  common  use  in  this 
country  do  not  include  methods  of  analysis 
for  oxygen  content  of  irons  and  steels.  This 
is  probably  due  to  the  fact  that  in  the  ordinary 
steel-making  processes  ferro-manganese  can  be 
freely  used,  so  that  it  is  assumed  that  the 
percentage  of  oxygen  in  the  steel  rarely  reaches 
or  exceeds  the  danger  point.  As  a  matter  of 
fact,  steel  often  carries  more  oxygen  than  it 
should,  as  can  be  seen  by  referring  to  Table  II. 

In  the  manufacture  of  iron  of  very  high 
purity  in  basic  open-hearth  furnaces  the  oxygen 
content  has  to  be  very  carefully  watched,  or 
the  product  may  be  overburned  and  contain  an 
excess  of  oxygen. 

A  number  of  methods  for  the  determination 
of  oxygen  have  been  proposed,  among  which 
may  be  mentioned:  (1)  Heating  the  sample 
in  a  stream  of  dry  chlorine;  (2)  Dissolving  the 
sample  in  special  solvents  such  as  copper 
sulphate  or  bromine;  (3)  Combustion  of  the 


*Paper  published  by  Allerton  S.  Cushman,  Journal  of  Industrial  and 
Engineering  Chemistry,  June,  1911. 

41 


sample   in    the   form    of   borings    in   pure    dry 
hydrogen. 

The  latter  method,  which  is  due  to 
Ledebur,*  is  the  only  one  that  has  proved 
reliable.  In  Ledebur's  original  method,  the 
sample  is  given  a  preliminary  combustion  in 
pure  nitrogen  in  order  to  burn  off  the  last 
traces  of  impurities  and  to  get  rid  of  all  hydro- 
carbons. If  the  preliminary  heating  in  nitrogen 
is  dispensed  with,  the  results  will  be  slightly 
higher,  but  it  is  probable  that  for  general  work 
sufficiently  accurate  results  can  be  obtained  if 
the  sample  is  carefully  prepared  for  the  com- 
bustion in  hydrogen. 

Samples 

The  samples  should  consist  of  fine  borings 
or  shavings  from  a  milling  machine.  The 
drill  or  machine  tool  should  be  scrupulously 
clean  and  free  from  all  traces  of  oil  or  dirt,  and 
should  be  geared  to  run  slowly  so  as  not  to 
heat  the  sample  while  it  is  being  cut.  Lack  of 
careful  attention  to  this  point  will  lead  to  high 
results  owing  to  surface  oxidation  of  the  fine 
particles  of  the  drillings. 

Apparatus 

The  apparatus  used  in  making  the  oxygen 
determination  is  shown  in  illustration  B-740. 


•"Leitfaden   fur  Eisenhuttenlaboratorien.      Vieweg    und    Sohn,  Braun- 
schwieg,  6  Auflage,  1903,  S.  122. 

42 


A  1 -gallon  Kipp  generator  is  used  for  gen- 
erating the  hydrogen.  It  should  be  charged 
with  drillings  of  pure  iron  or  mossy  zinc,  and 
dilute  hydrochloric  acid  (1-1).  Steel  turnings 
should  not  be  used  in  the  generator,  as  the 
object  is  to  generate  the  purest  possible  hydro- 
gen. Hydrochloric  is  preferable  to  sulphuric 
acid.  After  its  formation  the  hydrogen  is 
purified  and  dried  by  passing  through  the 
usual  train  as  shown  in  the  figure.  It  passes 
first  over  stick  potash,  and  next  through  a 
30%  potash  solution.  This  solution  in  the 
second  bottle  should  be  renewed  as  soon  as  it 
shows  a  tinge  of  yellow  due  to  the  presence 
of  sulphides.  The  hydrogen  next  passes  through 
concentrated  sulphuric  acid  to  dry  it,  and  then 
enters  a  silica  tube  with  J^"  bore,  30"  in  length, 
which  contains  a  roll  of  platinum  gauze.  The 
34"  tube  lies  on  top  of  a  1"  x  30"  fused  silica 
tube  contained  in  a  suitable  12"  gas  blast 
furnace. 

The  object  of  the  preliminary  heating  over 
platinum  foil  is  to  free  the  hydrogen  from  the 
small  quantity  of  oxygen  which  it  always 
contains.  If  this  precaution  is  not  taken,  the 
results  will  be  too  high.  The  water  formed  in 
the  small-bore  silica  tube  is  caught  in  a  U- 
tube  shown  in  the  figure,  which  contains  phos- 
phoric anhydride  opened  up  with  glass  wool. 

44 


This  drying  tube  has  rubber  stoppers.  The 
connection  is  made  with  pure  guni  tubing  and 
is  permanent*  the  sample  being  introduced  from 
the  opposite  end  of  the  combustion  tube. 

Blanks  should  be  run  from  time  to  time  to 
make  sure  that  the  apparatus  is  in  good  order 
and  everything  working  properly.  Samples 
should  not  be  introduced  into  or  removed  from 
the  combustion  tube  when  it  is  more  than 
hand  hot,  but  silica  tubes  may  be  quickly 
cooled  with  perfect  safety  by  turning  off  the 
gas  and  allowing  the  cold  air  blast  to  play  on 
the  tube. 

Method 

Weigh  20  to  30  grams  of  finely  divided 
borings  into  a  nickel  or  platinum  boat 
Y£  x  Y£  x  6".  The  boat  with  its  charge  is 
quickly  inserted  into  the  combustion  tube  and 
pushed  to  the  middle  zone  by  means  of  a  rod 
of  suitable  length.  The  stream  of  hydrogen 
should  be  passing  freely  when  the  tube  is 
opened  for  the  insertion  of  the  sample.  After 
the  stopper  is  replaced,  the  weighing  tube  and 
guard  tube  are  finally  connected  up  with  pure 
gum  tubing.  The  weighing  tube  is  a  4"  U- 
tube,  with  ground  glass  stoppers,  containing 
phosphoric  anhydride  opened  up  with  glass 
wool.  The  guard  or  trap  tube  is  similarly 


charged  and  is  intended  to  prevent  the  drawing 
back  of  moisture  from  the  air  of  the  laboratory. 
After  the  apparatus  is  all  connected  up  and  in 
good  order,  the  pure  dry  hydrogen  should  be 
allowed  to  sweep  through  a  few  minutes  until 
all  air  is  removed  from  the  entire  system. 
The  gas  is  then  lighted,  the  blast  turned  on 
and  the  temperature  quickly  run  up  to  a  bright 
red  heat,  about  850°  C.  This  heat  is  main- 
tained for  30  minutes,  while  the  hydrogen 
is  passing  through  the  apparatus  at  the  brisk 
rate  of  about  100  c.  c.  per  minute.  After  the 
combustion  is  completed  the  gas  is  turned  off 
the  furnace,  leaving  the  blast  playing  upon  the 
hot  tube.  The  stream  of  hydrogen  should 
continue  to  pass  until  the  tube  is  cool  enough 
to  bear  the  hand  upon  it. 

Immediately  after  the  tube  is  cool  enough, 
the  weighing  tube,  with  its  guard  tube,  is 
disconnected  and  connected  with  a  suitable 
aspirator,  so  as  to  suck  out  the  hydrogen  gas 
and  replace  it  with  dry  air.  A  suitable  aspirator 
consists  of  a  1 -gallon  aspirator  bottle  filled 
with  water.  The  upper  tubular  of  the  bottle 
is  guarded  with  a  calcic  chloride  tube  to  which 
the  weighing  tube  is  connected.  A  gas  washing 
bottle  containing  concentrated  sulphuric  acid 
follows  the  phosphoric  acid  tube  which  is  con- 
nected to  the  other  side  of  the  weighing  tube. 


46 


The  aspirator  may  be  roughly  calibrated  by 
allowing  about  500  c.  c.  of  water  to  run  out  of 
the  lower  tubular  of  the  aspirator.  A  sufficient 
quantity  of  perfectly  dry  air  is  drawn  through 
to  thoroughly  displace  all  the  hydrogen.  After 
all  is  ready,  the  weighed  tube  is  closed  by  its 
glass  stop-cocks,  disconnected  from  its  guard 
tube  and  placed  in  a  desiccator  for  15  minutes 
before  being  weighed.  Eight-ninths  of  the 
increased  weight  of  the  tube  is  oxygen.  The 
blanks  on  the  apparatus  establish  the  average 
correction  to  be  subtracted  from  the  weight 
found.  The  correction  on  an  apparatus  in  good 
order  should  not  exceed  3  milligrams.  On  damp 
days  the  blank  is  usually  a  little  higher  than 
when  the  air  is  dry. 

In  charging  the  weighing  tube  with  phos- 
phoric anhydride  and  glass  wool,  take  care  to 
remove  any  specks  of  phosphoric  acid  from  the 
upper  portions  of  the  tube. 

The  following  points  should  be  given  careful 
attention  in  order  to  attain  the  highest  degree 
of  accuracy: 

Samples  must  be  clean,  absolutely  dry  and 
free  from  oil.  They  should  be  cut,  preferably 
with  a  milling  machine  tool  running  at  a  low 
rate  of  speed.  The  samples  must  not  heat  in 
cutting.  Sheet  samples  are  first  cleaned  from 
oxide  on  an  emery  wheel,  avoiding  heating  as 


47 


much  as  possible.  The  sheet  should  be  milled 
on  the  edge. 

Whenever  possible,  samples  should  be  cut 
from  bars  which  are  first  cleaned  by  a  super- 
ficial cut  with  the  milling  tool.  Extreme  care 
must  be  taken  in  the  preparation  of  the  sample. 

The  entire  apparatus  must  be  kept  to  the 
top  notch  of  cleanliness,  tightness  and  general 
good  order.  Blanks  should  be  run  frequently. 
Analysis  should  be  in  duplicate  whenever  the 
results  are  to  be  used  as  a  basis  for  specification. 
The  most  extreme  care  should  be  taken  to 
exclude  all  oxygen  from  the  sample  and  appara- 
tus except  that  which  it  is  the  object  of  the 
method  to  determine.  When  determining  oxy- 
gen in  pure  iron,  the  silver  white  iron  residues 
from  the  boat  should  be  reserved  for  charging 
the  Kipp  hydrogen  generator. 


The  claim  has  been  made  that  the  modified  Ledebur  method  as 
described  above  does  not  determine  total  oxygen,  as  the  oxides  of 
manganese,  aluminum,  silicon,  titanium  and  other  possible  constituents 
or  impurities  of  steel  are  not  reduced  by  combustion  in  hydrogen. 
This  statement  is  true,  but  it  is  our  belief  that  only  the  oxygen  com- 
bined with  iron  measures  the  state  of  deoxidation  of  the  metal,  and 
that  a  method  of  analysis  which  determines  total  oxygen  in  steel  with- 
out differentiation  is  quite  valueless.  In  addition  to  this  it  must  be 
remembered  that  American  Ingot  Iron  is  essentially  free  from  oxides 
unreducible  by  combustion  in  hydrogen,  so  that  there  could  be  little  or 
no  difference  between  total  oxygen  and  oxygen  by  the  Ledebur  method 
in  the  case  of  a  metal  of  a  high  degree  of  purity. 

48 


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50 


Analysis  of  Tin  and  Terne  Plate 
and  Lead  Coated  Sheets 

Several  samples  exactly  2"  x  2"  should  be 
taken  for  analysis.  Clean  thoroughly  with 
carbon  tetrachloride  or  gasoline  and  weigh. 
A  400  c.  c.  Jena  glass  beaker  has  been  found 
the  most  convenient  for  this  test.  We  have 
found  that  20  c.  c.  of  concentrated  sulphuric 
acid  is  sufficient  for  each  2"  x  2"  piece.  If 
4  pieces  are  taken,  however,  60  c.  c.  of 
sulphuric  acid  will  be  sufficient.  Place  the 
requisite  amount  of  acid  in  the  beaker  and 
heat  to  at  least  250°  C.  Wrap  a  stiff  platinum 
or  nickel  wire  around  one  of  the  2"  x  2"  pieces 
so  that  it  can  be  placed  in  the  acid  in  a  hori- 
zontal position.  Immerse  the  piece  in  the  hot 
acid  for  exactly  1  minute.  Transfer  the  piece 
to  another  400  c.  c.  beaker  containing  25  c.  c. 
of  distilled  water  and  rub  the  surface  of  the 
sample  while  washing  with  about  50  c.  c.  more 
distilled  water,  using  a  wash  bottle  for  this 
purpose.  Dry  the  sample  thoroughly  and 
reweigh.  The  loss  in  weight  represents  the 
coating  and  some  iron.  Repeat  this  operation 
for  each  sample,  collecting  all  rinsings  in  a 
beaker,  and  reserve  for  analysis. 

The  iron  which  has  dissolved  is  determined 
as  follows:  The  sulphuric  acid  is  carefully 

51 


poured  into  the  beaker  containing  the  washings 
from  the  2"  x  2"  pieces.  This  solution  is  cooled 
and  poured  into  a  volumetric  flask.  25%  by 
volume  of  concentrated  hydrochloric  acid  is 
added  and  the  flask  filled  to  the  mark  with 
distilled  water.  If  4  pieces  have  been  taken  for 
analysis,  a  500  c.  c.  volumetric  flask  will  be 
required.  Use  a  proportionately  smaller  flask 
if  less  than  4  samples  are  analyzed.  Mix  thor- 
oughly, and  transfer  100  c.  c.  of  the  solu- 
tion to  a  300  c.  c.  Erlenmeyer  flask.  Add  a 
solution  of  tenth  normal  permanganate  until 
iron  and  tin  are  oxidized,  which  is  indicated  by 
the  appearance  of  a  permanent  straw  color. 
No  account  is  taken  of  the  amount  of  perman- 
ganate used.  Heat  to  boiling  and  reduce 
carefully  with  stannous  chloride.  Cool  and 
pour  into  a  1000  c.  c.  beaker  containing  500 
c.  c.  of  distilled  water  and  25  c.  c.  of  satu- 
rated solution  of  mercuric  chloride,  stir  vig- 
orously, add  50  c.  c.  of  the  titrating  mixture 
of  phosphoric  acid  and  manganese  sulphate,  and 
titrate  with  tenth  normal  permanganate  to  pink 
color.  The  amount  of  iron  which  has  thus 
been  determined  is  subtracted  from  the  total 
weight  lost  in  sulphuric  acid;  the  remainder  is 
coating.  It  is  very  often  unnecessary  to  make 
an  analysis  of  the  coating,  the  object  being 
merely  to  determine  the  weight. 

There   are   several   ways   of   expressing   the 
weight  of  the  coating;    we  prefer  to     express 

52 


it  in  ounces  per  square  foot.  By  knowing 
the  number  of  square  feet  in  a  box  of  tin  plate 
or  a  case  of  terne  plate  there  is  no  confusion 
in  converting  the  ounces  per  square  foot  to 
pounds  per  box  or  case.  The  coating  on  tin 
plate  is  sometimes  expressed  in  pounds  per  box 
of  112  sheets  14"  x  20".  This  figure  can  be 
obtained  by  multiplying  the  number  of  grams 
of  coating  of  each  2"  x  2"  piece  by  17.29.  If 
it  is  desired  to  express  the  coating  on  terne 
plate  in  pounds  per  case  of  112  sheets  20"  x  28", 
then  multiply  the  number  of  grams  of  coating 
on  each  2"  x  2"  piece  by  34.57.  The  average 
of  the  several  pieces  represents  the  weight  of 
coating. 

If  the  determination  of  tin  and  lead  is 
desired  in  the  sheet,  proceed  as  follows:  Place 
another  100  c.  c.  of  the  sulphuric  acid  solution 
containing  the  coating  in  a  300  c.  c.  Erlenmeyer 
flask.  Should  or  should  not  any  lead  sulphate 
be  removed  with  this  100  c.  c.,  does  not 
influence  the  accuracy  of  the  tin  analysis. 
Add  50  c.  c.  of  concentrated  hydrochloric  acid 
and  1  gram  of  finely  ground  antimony.  Connect 
flask  with  a  1-hole  stopper  containing  a  glass 
tube  bent  twice  at  right  angles,  the  end  of  which 
projects  into  a  beaker  of  water.  Boil  5  minutes 
and  replace  the  beaker  containing  the  water 
with  one  containing  an  8%  solution  of  bicar- 

53 


bonate  of  soda  prepared  from  boiled  distilled 
water.  Remove  flask  from  hot  plate  and  allow 
the  soda  water  to  flow  back  into  the  flask 
while  cooling  same  with  tap  water.  When  cold, 
add  a  few  c.  c.  of  starch  solution  and  titrate 
to  permanent  blue  color  with  tenth  normal 
iodine  solution.  1  c.  c.  equals  .00595  gram  of 
tin.  The  amount  of  tin  found  is  subtracted 
from  the  weight  of  coating  which  has  been 
determined  by  loss  in  sulphuric  acid,  and  after 
the  iron  correction  has  been  made  the  remainder 
is  lead.  An  example  of  a  regular  analysis  of 
terne  plate  is  as  follows: 

Piece  2"  x  2"  weighs 7 . 563  grams 

Same  after  stripped  in  acid  weighs. 6. 721  grams 

Loss   coating  plus  iron  weighs 842  grams 

Sulphuric  acid  and  washings  were  diluted 
to  200  c.  c.,  100  c.  c.  of  which  was  titrated  for 
iron.  This  required  10.1  c.  c.  of  tenth  normal 
permanganate,  which  is  equivalent  to  .0564 
gram  of  iron.  As  half  of  the  solution  only  was 
taken  for  analysis,  it  is  necessary  to  multiply 
by  2,  which  is  equivalent  to  .1128  gram  iron. 

Total  weight  of  coating  plus  iron. .  .  .  8420  gram 
Weight  of  iron  dissolved 1128  gram 

Coating 7292  gram 

.7292  x  34.57  =  25.21  pounds  coating  per 
case  of  112  sheets  20"  x  28". 

54 


The  tin  was  then  determined  in  50  c.  c.  of 
the  sulphuric  acid  solution.  This  required  7.8 
c.  c.  of  tenth  normal  iodine. 

7.8  x  .00595  x  4  -  -  .1856  gram  tin. 

Coating       Tin  Lead 

Grams     .7292  -  -  .1856  i  :  .5436 

By  knowing  the  original  weight  of  coating 
and  the  weight  of  tin  and  lead  in  this  coating, 
it  is  a  very  simple  matter  to  determine  the 
percentage  of  each  element. 

In  the  determination  of  tin  in  tin  plate  it  is 
only  necessary  to  determine  the  loss  in  sulphuric 
acid,  and  then  to  determine  the  iron  which  has 
been  dissolved,  the  remainder  being  tin. 

Heavily  coated  lead  sheets  may  require  twice 
as  much  acid  and  a  temperature  of  300°  C.  to 
completely  remove  the  coating  in  1  minute. 


PUDDLED  IRON 
Showing  Grains  of  Ferrite  and  Slag  Inclusions 


.50 


Test  to  Indicate  Whether  Metal 
is  Iron  or  Steel 

In  making  this  test  without  the  use  of  a 
balance  the  following  table  can  be  used  when 
metal  is  in  sheet  form  and  the  gauge  is  known. 
These  weights  represent  the  number  of  grams 
in  1  square  inch: 


Gauge    Grams 
Sq.  Inch 

Gauge    Grams 
Sq.  Inch 

Gauge   Grams 
Sq.  Inch 

12         14.00 

17           7.10 

22         4.00 

13         12.00 

18           6.40 

23         3.61 

14         10.00 

19          5.66 

24         3.20 

15           9.00 

20          4.82 

25         2.80 

16          8.00 

21          4.41 

26         2.41 

As  an  illustration,  suppose  we  have  16 
gauge  material.  A  square  inch  weighs  8 
grams,  hence  a  strip  ^g"  x  1"  weighs  approxi- 
mately 1  gram,  or  34"  x  V^  would  also  equal 
1  gram.  If  the  sheet  is  galvanized  the  coating 
need  not  be  removed  before  making  the  test. 

Take  equal  portions  of  American  Ingot  Iron 
and  sample  to  be  tested,  equal  to  ^  gram, 
and  place  in  separate  10"  x  1"  test  tubes.  Add 
to  each  tube  15  c.  c.1  of  dilute  nitric  acid,  1.18 
specific  gravity2.  Place  a  test  tube  in  holder, 
using  care  to  incline  the  tube  away  from 


57 


spectators  while  being  heated  with  an  alco- 
hol lamp.  The  metal  will  disappear  in  a 
few  minutes,  but  continue  heating  until  no  more 
brown  fumes  are  given  off.  Allow  solution 
to  cool  and  heat  the  other  tube  in  same  manner 
and  cool.  The  solutions  can  be  compared  at 
this  point,  the  darker  one  containing  the  highest 
per  cent  of  carbon. 

To  each  test  add  Y^  gram  sodium  bis- 
muthate3  and  agitate  for  a  few  minutes.  Then 
add  sufficient  water  to  half  fill  the  tubes  and 
mix  thoroughly.  Allow  the  tubes  to  rest  for 
several  minutes  until  the  undissolved  sodium 
bismuthate  settles.  By  comparing  the  clear 
solutions,  American  Ingot  Iron  will  show  a 
light  pink  color,  while  steel  will  yield  a  purple 
color  due  to  manganese  present. 


1.  If  no  graduate  is  available,  the  volume  of  acid  can  be  estimated  by 
noting  the  depth  of   I"  diameter  tube;  each  inch   is  equal   to  about 
10  c.  c. 

2.  1.18  specific  gravity  nitric  acid   can  be  prepared  by  adding  1  part 
1.42  specific  gravity  nitric  acid  to  2  parts  water. 

3-     %  gram  sodium  bismuthate  is  about  the  maximum  amount  that  can 
be  placed  on  a  dime. 

58 


Pin  Hole  Test — Lead  Coated,  Tin 
and  Terne  Plate 

Dr.  Allerton  S.  Cushman  has  devised  a  very 
simple  test  to  determine  the  number  of  pin 
holes  per  square  foot.  The  test  consists  of 
exposing  a  full  sized  sheet  to  the  action  of 
distilled  water.  The  pin  holes  appear  as  rust 
spots. 

The  four  sides  of  the  sheet  are  bent  so  as  to 
make  a  pan  1"  deep.  The  pan  is  thoroughly 
cleaned  with  several  applications  of  gasoline  and 
then  flooded  to  a  depth  of  J^n  with  distilled 
water.  After  1  week's  exposure  the  water  is 
removed  and  the  pin  holes  are  counted. 


59 


Hydrochloric  Acid   Method  for  Deter- 
mining Ounces  of  Spelter 
per  Square  Foot 

Take  about  10  samples  of  exactly  2"  x  2" 
from  each  sheet,  weigh  all  samples  together  and 
place,  one  at  a  time,  in  200  c.  c.  of  concentrated 
hydrochloric  acid  for  exactly  1  minute,  turning 
samples  over  during  test.  Remove  samples 
from  acid,  wash  carefully,  scrub,  dry  and  weigh. 
The  loss  in  weight  is  coating,  which,  divided 
by  the  number  of  pieces  used  and  multiplied 
by  1.27,  gives  ounces  per  square  foot. 

This  method  is  especially  recommended  for 
the  determination  of  spelter  on  American  Ingot 
Iron  on  account  of  the  slight  solubility  of  pure 
iron  in  hydrochloric  acid. 

If  the  spelter  is  to  be  determined  upon 
Bessemer  or  other  steel  readily  acted  upon  by 
hydrochloric  acid,  this  method  is  not  recom- 
mended, and  the  lead  acetate  method  should 
be  used. 


60 


Lead  Acetate  Method  for  the  Determi- 
nation of  Spelter  Coating 

The  basis  of  this  test  is  as  follows: 

When  a  zinc-coated  iron  article  is  placed 
in  this  solution  at  ordinary  temperatures,  the 
zinc  passes  into  solution,  and  an  equivalent 
amount  of  metallic  lead  is  precipitated  in  a 
loosely  adherent  form  upon  the  specimen. 
The  reaction  is  retarded  by  the  precipitation  of 
the  lead,  and,  therefore,  when  a  heavily  gal- 
vanized piece  is  being  tested,  this  lead  must  be 
periodically  removed.  The  acetate  solution  can 
be  used  to  measure  by  time  just  as  the  Preece 
copper  sulphate  solution,  if  desired.  Should 
lead  plate  on,  it  is  not  easily  confounded  with 
the  bright  iron  when  exposed.  The  uncovering 
of  the  iron  can  be  readily  detected. 

The  solution  used  for  making  this  test  is 
prepared  by  dissolving  400  grams  of  crystallized 
lead  acetate  in  1  liter  of  water.  When  dis- 
solved, add  4  grams  of  finely  powdered  lith- 
arge and  agitate  until  most  of  it  has  dissolved. 
The  solution  is  allowed  to  settle  and  the  clear 
portion  decanted  for  use. 

Ordinary  glass  tumblers  have  been  found 
very  satisfactory  to  use  in  making  this  test, 
as  they  are  the  right  diameter  to  enable  the 

61 


sample  to  be  maintained  in  an  upright  position 
without  supports. 

The  samples  should  be  taken  from  various 
parts  of  the  sheet.  Use  several  2"  x  2"  pieces 
cut  accurately  to  -^]].  Weigh  the  samples 
together  and  submerge  separately,  for  3  minutes, 
in  tumblers  containing  solution  of  lead  acetate. 
The  samples  are  then  taken  out  and  the  adher- 
ent lead  removed  with  a  stiff  brush  or  steel 
spatula.  A  burnishing  action  should  be 
avoided,  as  under  some  conditions  closely 
adherent  lead  will  be  plated  out  on  the 
iron.  Repeat  the  3-minute  immersions  in  the 
lead  acetate  solutions  until  a  bright  surface  is 
exposed.  Four  3-minute  immersions  are  usually 
sufficient.  Wash  specimens  in  water,  dry  and 
weigh.  The  loss  in  grams  represents  the  coating, 
which,  divided  by  the  number  of  2"  x  2"  pieces 
used  and  multiplied  by  1.27,  gives  the  number 
of  ounces  of  coating  per  square  foot. 


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